Clarification on DTMF

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prasannabalaji

Joined: 19 Dec 2006
Posts: 15

19 Feb 2007 10:17 Clarification on DTMF

hi,

i am using MT8880 which is a DTMF transceiver..after initialisation of control reg i am giving the input of 7 i want to know, how to check that wheather this IC is txansmitting DTMF signal or not

thank u in advance

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Prabakaran

Joined: 22 Jan 2007
Posts: 160
Helped: 5
Location: Chennai(India)

24 Mar 2007 6:11 Clarification on DTMF

Hi
Prasannabalaji,
check the MT8880 by using the CRO , check the output of DTMF and u can see there is some frequency comming out from that.

Can u send the details of MT8880 , its cost and circuit diagram of this , because i too using the same module , i couldn get the IC in the Market. so can u send the details regarding the cost of the IC and place where u got the Ic , and send me the Application circuit.

pronab

Joined: 03 Nov 2006
Posts: 46
Helped: 1

29 Mar 2007 10:18 Re: Clarification on DTMF

i ned also the same

vinunandakumar

Joined: 13 Mar 2008
Posts: 14
Helped: 1

27 May 2008 18:59 Re: Clarification on DTMF

prasannabalaji wrote:

try using a dtmf decoder like 8870

saubhik

Joined: 27 Apr 2007
Posts: 141
Helped: 8
Location: India

28 May 2008 4:09 Re: Clarification on DTMF

A question which made me mad on my college days when I was doing the project on DTMF receiver.
After that what idea we have used I can explain it to u , I think it will help u to find out the answer very easily .

In a DTMF transmitter for any key press it generates two frequency signals (in Rake Receiver concept those signals are orthogonal to each other ) - one is of high frequency and another is of low frequency . Then if you know the frequecy range and what frequency the TX should generate then easily using filters u can separate the frequency signals and check in a CRO at the output of the filters ,. This method will help u to get the exact frequencies generated by the Tx.

Any how for ur help I am sending u the DTMF decoder IC details also which is preferred by Mr. vinunandakumar .....u can find it in the following link
http://www.edaboard.com/viewtopic.php?p=843910#843910

I hope u can right now easily solve the problem ......

Ok and Bye ......